Cut-off gear fob



.reference being had to the accompanying narran entras T CFFIC.,

P. W. GATES, D'. R. FRASER, AND THOS. CHALMERS, OF CHICAGO, ILLINOIS.

CUT-OFF GEAR FOR Specification of Letters Patent No.

To all whom it may concern.

Be it known that we, P. W. GATES, D. R. FRASER, and THOMAS CHALMERS, ofChicago, in the .county of Cook and State of Illinois, have invented anew and Improved Variable Cut-@ff Gear for Steam-Engines; and we dohereby declare that the following is a full, clear, and exactdescription of the Same,

drawings, making part of this specication, in which Figure l is a frontelevation. Fig. 2 is a vertical Section in a plane at right angles toFig. l. Fig. 3 is a horizontal section in the plane indicated by theline in Fig. 1. Fig. l is a back view of the rocking frame and itsappendages by which the cutoff valve is lifted.

Similar letters of reference indicate corresponding parts in the severalfigures.

This invention consists in a novel construction of two slidingtoe-pieces and a mode of applying the same to a rocking frame operatedby the steam-engine, in coinbination with a double lifter attached tothe stem of the cut-ofta valve and with a governor or other regulatingapparatus .to produce and vary the action of the cut-off for the purposeof controlling the speed of an engine.

To enable others skilled in the art to apply our invention to use, wewill proceed to describe its construction and operation.

A, is a valve box containing the cut-off valve which may be of thebalanced puppet or any other known kind, and therefore does not need tobe shown. This valve box is intended to be placed on the valve chest ofa steam engine or otherwise applied so that all the steam supplied tothe engine must pass through its valve.

. B is the valve stem working vertically through the top of the box A,and entering a box C, which is attached to the valve-box by standards F,F, and within which the stem has attached to its upper end a crossheadD, to the ends of which are attached two guide rods E, E, which areparallel with the valve Stem and which pass through guide holes in thebottom of the said box C. The lower parts of these rods E, E, have screwthreads cut upon them and are fitted with nuts b, o, between which andthe bottom of the box C, there are spiral springs a, a, coiled upon saidrods for the purpose of exerting a downward pressure upon the valve stemto STEAM-ENGINES.

22,361, dated neeember 21, 1815s.

close the valve. The box C is merely to inclose the crosshead and theupper ends of the valve stein and guide rods, and its bottom containsthe guides for said stem and rods to prevent the stem turning.

G, is a crosshead secured to the valve stem and having its ends bentlaterally at right angles as shown at e, e', in Fig. 3, to make itconstitute a double lifter.

H, is a rock shaftarranged horizontally with its axis in the same planeas the axis of the valve stem, and I is a bearing which supports thesaid rock shaft. This rock shaft carries the rocking frame J, to whichare litted the two sliding toe-pieces L, L,

which by the rocking motion of the frame J, are made to act alternatelyupon the projections c, e, of the lifter; L, upon e, and L upon e, andthus lift the valve open. These toe-pieces are fitted to slide past eachother in a longitudinal recess formed in the back of the rocking frameand are furnished with tail-like pieces z, t, which project down wardthrough an opening in the bottom of the recess in the frame in such amanner that they stand on opposite sides of a roller e', fitted to astud j, which is attached to a slide, M, that is fitted to slide up anddown on the valve stem. The faces of the said tail-like pieces which arenext to the roller are inclined so as to approach each other towardtheir lower extremities, as shown in Figs. l and 4. The toes la, 7c', onthe toe-pieces have angular extremities which are arranged to act uponthe bent extremities e, e', of the lifter.

rlhe toe-pieces are secured in the frame Gr, by screws f, f, which passthrough slots g, g, in the said frame and screw into the said pieces;and the screws f, f, serve to attach to the toe pieces a spring N, whichexerts a tendency to force them toward the ends of the frame as far aspermitted by their tails 7L, L, which come in contact with the rollerz', on the op-posite side to their respective toes lc, 7c.

The rockshaft H is furnished with an arm P, which is intended to beconnected with an eccentric on the crankshaft of the engine or to havesome connection with the engine which will cause it to oscillate onceback and forth during every revolution thereof so that the toes actingupon the lifters will lift the cut-off vavle to admit steam to thecylinder for ever Y stroke of the piston.

The slide M, is connected with a rod Z,

which may be supposed to be connected with a governor or provided with ascrew adjustment to raise or lower said slide and its stud j, and rollerz'. here is a stationary slotted guide R, attached to the top of thevalve box A, for the roller z', to work in, to keep the slide M, fromturning on the valve stem.

The operation is as follows: As the toe pieces L, L, are caused to liftthe valve by their action below the laterally projecting ends e, e', ofthe lifters, produced by the rocking movement of the frame J, their toes7e, c, are caused, both by the arc-formed movement of the rocking frameand by reason of the toe-pieces being drawn into the frame by the actionof their respective taillike pieces L, fr', against the roller z', asthe toes are raised, to slide under the ends e, e, until the toes, ifthe roller i, is not too high up, slip from under the laterallyprojecting ends e, c', and let the valve drop suddenly and close. Fig. lshows the toe 7c, as just about to escape from the end e, and let thevalve drop. As the toes descend with the rocking movement of the frameJ, they work down the inner faces of the projection e, and are therebyforced into the frame J, until, after working clear of the said faces,the spring N, forces them out again to positions to act under the saidprojections e, e, as they rise again. The time of the escape of the toesto let the valve drop depends upon the position of the stud j, androller i; the lowering of the said st-ud and roller between the inclinedsurfaces of the tail pieces 7L, 72,', forcing them farther apart, andthereby drawing in the toe-pieces so that they will escape earlier inthe stroke of the piston, and the raising of said stud and rollerproducing an opposite effect. The stud and roller may be raised so highas to permit the spring N, to keep the'toe-pieces always so far outas toprevent the escape of the toes and compel the valve to be loweredgradually, as well as raised, by the toes, and thus permit the piston towork under a full head of steam throughout the Whole stroke. In applyinga governor, the rod is so connected with it as to lower the slide M,

and the attached stud y', and roller z', as any

